Interlock system



United States Patent O INTERLOCK SYSTEM Eldred H. Comstock, Jr., South Daytona, Fla., and Raymond G. Martin, Baltimore, Md., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Oct. 5, 1965, Ser. No. 493,281 8 Claims. (Cl. 317-18) The present invention is a continuation-in-part application of a patent application entitled, Interlock System, Ser. No. 224,581, filed Sept. l8, 1962 now abandoned.

The present invention relates to an interlock system and more particularly to an electrical interlock device for use in a high voltage system having a plurality of power supplies that each supply a plurality of module loads.

Various safety systems have been employed in the past that require the operation or movement of various parts before access may be had to -a major piece of equipment. In one type of generally known interlock system, disconnect switches associated with a circuit breaker are interlocked in such a manner as to require the circuit to be opened at the circuit breaker before access could be had to the switches. After the circuit is opened, the breaker is locked open and then the associated disconnect switches are lock-ed open, in sequence. The breaker can then be unlocked to permit testing or repairing. This type of interlock system requires a lock for each movable part and the locks are so related that each piece of equipment is locked in its safety position beforea key can 'be released to operate a succeeding lock.

A variation of the above-described interlock system is shown in U.S. Patent 2,166,061, which issued July 1l, 1939, to Ralph L. Kirk. This patent describes an' interlock system in which the keys for unlocking the several devices are released upon the successive actu-ation of the devices in predetermined order. When applied toa circuit breaker system, the device described in the patent provides an interlock which may 'be actuated to obtain isolation of the -circuit breaker by locking open both disconnecting switches when work is to be done upon the circuit breaker itself. Also, the system will permit reclosing of the circuit breaker after locking open one disconnecting switch.

The present invention relates to la personnel safety interlocking system for use with a large number of high voltage power supplies that have inputs through an equal number of circuit breakers localized vin a central distribution switchboard. The power supplies, in turn, supply high voltage power to several groups of module loads, each group being remote from the other group. When a module becomes faulted, it is necessary that power to the appropriate power supply 'be secured Iand that it remain secured until the maintenance operation is -completed and all personnel `are clear. The present invention prevents access to the high voltage areas until it is certain that these -areas are deenergized and likewise, the present invention makes it `impossi-ble to 'accidentally energize the high voltage areas until it is safe to do so.

lIn the present invention, a plurality of loads are secured to a frame and the loads are constructed such that none o-f the electrical components are accessible until the connector to the load is removed. After removing the connector, a panel or cover can be removed and the inner components are then accessible for repair. When there is a fault, the circuit breaker, whic-h is located in the input line to the high voltage power supply that is feeding the fault, is unlock-ed, thus opening the circuit breaker 3,327,169 Patented June 20, 1967 an-d the key is then removed and taken to the lfault area. The same key is then used to actu'ate a second lock which secures a locking bar against rotation. After unlocking, the locking bar is rotated one-quarter revolution, which then frees a plurality of locking rings which can then be individually rotated. A plurality of connectors, which connect one each to separate loads, are individually connected to separate locking rings through arms. Rotation of the locking ring causes rotation of the arms which, in turn, causes the connectors to be separated -from their loads and thus permit access for repairing said loads. Rotation of the locking bar also causes -a switch to 'be actuated that is electrically connected between the high voltage power supply and a group of loads.

It is therefore a general object of the present invention to provide an improved interlock system for use with a plurality of electrical loads.

Another object of the present invention is to provide an interlock system for a plurality of loads that can be operated with a single key.

Still another object of the present invention is to provide an interlock system that provides access to a plurality of loads only when a high voltage power supply is disconnected from said loads.

Other objects and advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIGURE la is a block diagram showing a high voltage power supply system feeding a plurality of loads;

FIGURE 1b is a 'block diagram showing a plurality of loads in a module group;

FIGURE 2 is -a side view, partially broken away, showing a locking arrangement;

FIGURE 3 is a sectional view taken on line 3-3 of FIGURE 2; v

FIGURE 4 is a `sectional view taken on line 4 4 of FIGURE 2; and

FIGURE 5 is a sectional view similar to FIGURE 4 only showing a locking bar rotated approximately ninety degrees.

Referring t-o the drawing, wherein like reference characters designate like or corresponding parts throughout the several views, there is shown in FIGURES la and lb three high voltage power supplies 11, 12, and 13, that feed a plurality of loads which are shown as module groups 14 through 22. It should be understood, lof course, that three power supplies and nine module groups have been chosen for purposes of illustration only and that a lesser or greater number may be used without departing from the scope of the invention. Power supplies 11-13 are connected to a source of voltage V1 through input lines 23, 24, and 25, respectively, that are provided with circuit breakers 26, 27, and 28. Module groups 14 through 22 are connected through switches 31-39, respectively, to the outputs of power supplies 11, 12, and 13, as shown.

Referring now to FIGURE 2 of the drawing, there is shown a locking bar 41 that is rotatably mounted to frame 42 by means of bearings 43 and 44. As best shown in FIGURE 3 of the drawing, locking bar 41 is provided with first and second detents 45 and 46 that are spa-ced ninety degrees apart, and a latch 47 of a master lock 48 is engageable with the detents. Locking rings 51, 52, and 53 lare rotatably mounted on locking bar 41 and pins 54 are provided to limit both the direction and amount of rotation of the locking rings. Connector arms 55, 56, and 57 are attached, respectively, to locking rings 51, 52, and 53, and electrical connectors 61, 62, and 63 are provided on the ends of the connector arms. Connectors 61, 62, and 63 are connectable with loads 64, `65, vand 66, which are connected in parallel through switch 31. Loads 64, 65, and 66, are mounted on stands 67 and 70 that are attached to frame 42. Loads 64, 65, and 66 can be repaired only after first removing the respective connector attached thereto. Switch 31 is actuated by linkage 68 when locking bar 41 is rotated.

In operation, assuming that load-66 in module group 14 is in need of repair, circuit breaker 26 is unlocked and opened, which then cuts oi the input power to power supply 11. The key can then be removed from circuit breaker 26 and used to unlock lock 48. The circuit breaker 26 lock is constructed and arranged so that its key can 'only be removed when the circuit breaker is open. When lock 48 is unlocked, latch 47 is withdrawn from locking bar 41 which is then free to be rotated ninety degrees in a clockwise direction. Rotation of locking bar 41 in a clockwise direction causes switch 31 to be opened through the operation of linkage 68. Lock 48 can then be locked and latch 47 will engage with detent 46. As shown in FIGURE 5 of the drawing, locking ring 53 can now be rotated ninety `degrees in a -clockwise direction, and consequently, connector arm 57 is rotated ninety degrees thus separating connector 63 from load 66. Load 66 is now accessible and can be repaired. As shown in FIGURES 4 and 5 of the drawing, the locking rings each have a slot 71 that serves as a clearance for pins 54 Iand permit rotation of the locking rings relative to the locking bar 41.

Assuming now that load 66 has been repaired, lockingring 53 is rotated in a counterclockwise direction, and likewise connector arm 57 is rotated so that connector 63 engages with load 66. Lock 48 is then unlocked, which retracts latch 47 and locking bar 41 is rotated in a counterclockwise direction. Rotation of locking bar 41 causes switch 31 to be closed, and the lock 48 is vlocked so that latch 47 engages with detect 45. The key can then be removed from lock 48 and then returned to circuit breaker 26, which is then closed to put the system back into operation.

Lock 48 is constructed so that its key can be removed lonly when latch 47 is extended. When latch 47 is engaged with detent 46, switch 31 is open, thus if the key is inadvertently removed and used to close circuit breaker 26, no power will be applied to load 64.

It can thus be seen that the present invention provides an interlock device for a high voltage system that permits power to be applied only when the system is in a safe condition, that is, all electrical connections have Ybeen closed. Furthermore, the present invention eliminates any confusion which might be caused by having `a multiple number of keys.

Obviously many modifications and variations of the present invention are possible in the light of the above teaching. It is therefore to be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as speciically described.

What is claimed is:

1. An interlock system for use with an electrical circuit comprising:

a frame,

a locking bar rotatably mounted to said frame,

means for locking said locking bar in a first and a second position,

a plurality of loads,

a plurality of connectors, one each connectable with each said load, and

means attached to said locking bar for preventing removement of said connectors from said load when said locking bar is locked in said rst position.

2. An interlock system for use with an electrical circuit as set forth in claim 1 wherein said means for locking said locking bar in a iirst and .a second position comprises rst and second detents in said locking bar and a master lock having means for retaining a key against release except when said master lock is engaged with one of said detents.

3. An interlock system for use with an electrical circuit as set forth in claim 1 wherein said means attached to said locking bar for preventing removement of said connectors from said load when said locking bar is locked in said first position comprises a plurality of locking rings rotatably mounted on said locking bar; a plurality of pins, one each for each said locking ring, attached to said locking bar and limiting rotation of said locking rings; and a plurality of connector arms, one each connecting each said locking ring and each said connector.

4. An interlock system for use with an electrical circuit comprising:

a source of high voltage,

a frame,

a locking bar -rotatably mounted to said frame,

means for locking said locking bar in a rst and a second position,

a plurality of electrical loads connected to said sour-ce of high voltage,

a plurality of connectors, one each connectable with each said load,

means attached to said locking bar for preventing removement of said connectors from said load when said locking bar is l-ocked in said rst position,

switching means connected between said source of high voltage and said plurality of electrical loads, and

means attached to said locking bar for vactuating said switching means when said locking bar is rot-ated.

5. An interlock system for use with an electrical circuit as set forth in claim 4 wherein said means for locking said locking bar in a first and a second position cornprises tirst and second detents in said llocking bar and a master lock having means for retaining a key against vrelease except when said master lock is engaged with one of said detents.

6. An interlock system for use with an electrical circuit as set forth in claim 4 wherein said means attached to said locking bar for preventing removement of said connectors from said load when said locking bar is `locked in said first position comprises a plurality of locking rings rotatably mounted on said locking bar; :a plurality of pins, one each for each said locking ring, attached to said locking bar and limiting rotation of said locking rings; and a plurality of connector arms, one each connecting each said locking ring and each said connector.

7. 15in' interlock system for use with an electrical circuit composing:

ahigh voltage power supply having an input line and an output line,

a circuit breaker in said input line Ihaving a key operated lock unit having a key and means `for retaining said key against withdrawal except when said circuit breaker is locked open,

a frame,

a locking bar rotatably mounted to said frame,

a second key operated lock for locking said locking bar in a first and a second position, said second key operated lock being operated by said key that operates said circuit breaker,

a plurality of electrical loads,

a plurality of connectors, one each connectable with each said load, said connectors being connected in `series through a switch to said output line of said power supply,

means attached to said locking bar for preventing removement of said connectors from said load when said locking bar is locked in said rst position, and

means attached to said locking bar for actuating said switch when sai-d locking bar is rotated.

8. An interlock system for use with an electrical circuit as set forth in claim 7 wherein said means attached to said locking bar for preventing removement of said connectors from said load when said locking bar is locked in said first position comprises `a plurality of locking rin-gs ro- 5 tatably mounted on said locking bar; a plurality of pins, one eac-h for each said locking ring, attached to said locking bar and limiting rotation of said locking rings; and a plurality of connector arms, one each connecting each said locking ring and each said connector.

References Cited UNITED STATES PATENTS 1,976,609 l0/ 1934 Gates =307-94 2,068,581 1/1957 Tritle 317-136 3,033,978 5/1962 Van Ousen 104-115 X 3,246,178 4/1966 Comstock et al. 317-136 X MILTON O. HIRSHFIELD, Primary Examiner.

10 R. V. LUPO, Assistant Examiner. 

1. AN INTERLOCK SYSTEM FOR USE WITH AN ELECTRIC CIRCUIT COMPRISING: A FRAME, A LOCKING BAR ROTATABLY MOUNTED TO SAID FRAME, MEANS FOR LOCKING SAID LOCKING BAR IN A FIRST AND A SECOND POSITION, A PLURALITY OF LOADS, A PLURALITY OF CONNECTORS, ONE EACH CONNECTABLE WITH EACH SAID LOAD, AND MEANS ATTACHED TO SAID LOCKING BAR FOR PREVENTING REMOVEMENT OF SAID CONNECTORS FROM SAID LOAD WHEN SAID LOCKING BAR IS LOCKED IN SAID FIRST POSITION. 